Assuming that the equinox marked the first day of spring in certain medieval cultures, as it does now in western countries, Groundhog Day occurred exactly 6 weeks before spring. Therefore, if the groundhog saw his shadow on Groundhog Day there would be 6 more weeks of winter. If he didn’t, there would be 42 more days of winter. In other words, the Groundhog Day tradition may have begun as a bit of folk humor.